Descent With Modification: a Darwinian View of Life Chapter 22 BCOR 012 A January 21, 2011.

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Presentation on theme: "Descent With Modification: a Darwinian View of Life Chapter 22 BCOR 012 A January 21, 2011."— Presentation transcript:

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Descent With Modification: a Darwinian View of Life Chapter 22 BCOR 012 A January 21, 2011

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In 1645, Bishop Ussher of Ireland stated that the Earth must have been created on October 26th, 4004 BC.

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Jean Baptiste Lamarck 1744-1829 Curator at the Natural History Museum in Paris “… Nature has in favorable times, places, and climates multiplied her first germs of animality, given place to developments of their organizations,... and increased and diversified their organs. Then... aided by much time and by a slow but constant diversity of circumstances, she has gradually brought about in this respect the state of things which we now observe. Text of a lecture given by Lamarck at the Musée National d'Histoire Naturelle, Paris, May 1803

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William Smith’s map - inferring a vertical sequence upward from older to younger rocks. Jurassic beds near Lyme Regis on the south coast of Dorset, England, and ammonites from one of the beds. While studying these beds and others about 1800, William Smith developed the concept of "guide fossils."

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Georges Cuvier (1769-1832) and Alexandre Brongniart (1770-1847) early recognized the phenomena of restriction of distinctive fossils to particular zones, formations or series — guide fossils — and applied this tool in their stratigraphical studies. Moreover, they observed a pattern or trend in the change from level to level. Of the shells found in the upper, more recent levels, he states that the "eye of the most expert naturalist cannot distinguish from those which at present inhabit the ocean." Forms of life recovered from successively more ancient strata were observed to become progressively more strange and "peculiar" (Cuvier 1817:13, 108-109).

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Darwin’s Beagle Voyage Observations: Geographic regions have distinctive floras and faunas Islands are centers of endemism Organisms are adapted to the conditions under which they live Geographically neighboring regions have related species.

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Charles Lyell, 1797-1875 UNIFORMITARIANISM Hutton and Lyell’s influence on Darwin: The idea that slow processes operating over vast periods of time could produce great changes.

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Five premises underlying Darwin’s theory: Variability: Populations of organisms are variable Heritability: Some of the variable traits are passed from generation to generation Overproduction: More individuals are produced in a population than will survive to reproduce Competition: Individuals compete for limited resources Differential Survival: Those individuals better suited to their environment will leave more descendents than less well suited individuals.

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Darwin reasoned that if, under artificial selection, so much change could be produced in a relatively short time, than what a great amount of change should be possible over hundreds of thousands of generations!

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Two main features of the Darwinian view of life: The diverse forms of life have arisen by descent with modification from ancestral species The mechanism of modification has been natural selection operating over immense spans of time

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Evolution Explains Three Key Observations About Life: The good “fit” of organisms to their environment (adaptation) The unity ( shared characteristics ) of life The diversity of life

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JAMES HUTTON 1726-1797 Geologist, chemist, naturalist, father of modern geology GRADUALISM Hadrian’s wall Hadrian wished to consolidate his boundaries. He visited Britain in 122 AD, and ordered a wall to be built from west to east "to separate Romans from Barbarians".

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Charles Lyell, 1797-1875 UNIFORMITARIANISM Hutton and Lyell’s influence on Darwin: The idea that slow processes operating over vast periods of time could produce great changes.

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Georges Cuvier (1769-1832) recognized the restriction of distinctive fossils to particular geological series. Moreover, he observed a pattern in the change from level to level. Of the shells in the upper, more recent levels, he states, " the eye of the most expert naturalist cannot distinguish from those which at present inhabit the ocean." Forms of life recovered from successively more ancient strata were observed to become progressively more strange and "peculiar" (Cuvier 1817:13, 108- 109).